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Add XSIMD implementation

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mancini
2025-08-07 14:30:28 +02:00
parent b7c13be6c0
commit b55f456178
8 changed files with 255 additions and 0 deletions
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src/lookup_xsimd.cpp Normal file
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#include <algorithm>
#include <cmath>
#include <vector>
#include <xsimd/xsimd.hpp>
#include "trigdx/lookup_xsimd.hpp"
template <std::size_t NR_SAMPLES> struct lookup_table {
static constexpr std::size_t MASK = NR_SAMPLES - 1;
static constexpr float SCALE = NR_SAMPLES / (2.0f * float(M_PI));
lookup_table() : values{} {
for (uint_fast32_t i = 0; i < NR_SAMPLES; i++) {
values[i] = sinf(i * (2.0f * float(M_PI) / NR_SAMPLES));
}
}
std::array<float, NR_SAMPLES> values;
};
template <std::size_t NR_SAMPLES> struct cosf_dispatcher {
constexpr cosf_dispatcher() : lookup_table_(){};
template <class Tag, class Arch>
void operator()(Arch, const size_t n, const float *a, float *c, Tag) const {
using b_type = xsimd::batch<float, Arch>;
using m_type = xsimd::batch<int32_t, Arch>;
constexpr uint_fast32_t VL = b_type::size;
const uint_fast32_t VS = n - n % VL;
const uint_fast32_t Q_PI = NR_SAMPLES / 4U;
const b_type scale = b_type::broadcast(lookup_table_.SCALE);
const m_type mask = m_type::broadcast(lookup_table_.MASK);
const m_type quarter_pi = m_type::broadcast(Q_PI);
uint_fast32_t i;
for (i = 0; i < VS; i += VL) {
const b_type vx = b_type::load(a + i, Tag());
const b_type scaled = xsimd::mul(vx, scale);
m_type idx = xsimd::to_int(scaled);
m_type idx_cos = xsimd::add(idx, quarter_pi);
idx_cos = xsimd::bitwise_and(idx_cos, mask);
const b_type cosv = b_type::gather(lookup_table_.values.data(), idx_cos);
cosv.store(c + i, Tag());
}
for (; i < n; i++) {
std::size_t idx = static_cast<std::size_t>(a[i] * lookup_table_.SCALE) &
lookup_table_.MASK;
std::size_t idx_cos = (idx + Q_PI) & lookup_table_.MASK;
c[i] = lookup_table_.values[idx_cos];
}
}
lookup_table<NR_SAMPLES> lookup_table_;
};
template <std::size_t NR_SAMPLES> struct sinf_dispatcher {
constexpr sinf_dispatcher() : lookup_table_(){};
template <class Tag, class Arch>
void operator()(Arch, const size_t n, const float *a, float *s, Tag) const {
using b_type = xsimd::batch<float, Arch>;
using m_type = xsimd::batch<int32_t, Arch>;
constexpr uint_fast32_t VL = b_type::size;
const uint_fast32_t VS = n - n % VL;
const uint_fast32_t Q_PI = NR_SAMPLES / 4U;
const b_type scale = b_type::broadcast(lookup_table_.SCALE);
const m_type mask = m_type::broadcast(lookup_table_.MASK);
const m_type quarter_pi = m_type::broadcast(Q_PI);
uint_fast32_t i;
for (i = 0; i < VS; i += VL) {
const b_type vx = b_type::load(a + i, Tag());
const b_type scaled = xsimd::mul(vx, scale);
m_type idx = xsimd::to_int(scaled);
idx = xsimd::bitwise_and(idx, mask);
const b_type sinv = b_type::gather(lookup_table_.values.data(), idx);
sinv.store(s + i, Tag());
}
for (; i < n; i++) {
std::size_t idx = static_cast<std::size_t>(a[i] * lookup_table_.SCALE) &
lookup_table_.MASK;
s[i] = lookup_table_.values[idx];
}
}
lookup_table<NR_SAMPLES> lookup_table_;
};
template <std::size_t NR_SAMPLES> struct sin_cosf_dispatcher {
template <class Tag, class Arch>
void operator()(Arch, const size_t n, const float *a, float *s, float *c,
Tag) const {
using b_type = xsimd::batch<float, Arch>;
using m_type = xsimd::batch<int32_t, Arch>;
constexpr uint_fast32_t VL = b_type::size;
const uint_fast32_t VS = n - n % VL;
const uint_fast32_t Q_PI = NR_SAMPLES / 4U;
const b_type scale = b_type::broadcast(lookup_table_.SCALE);
const m_type mask = m_type::broadcast(lookup_table_.MASK);
const m_type quarter_pi = m_type::broadcast(Q_PI);
uint_fast32_t i;
for (i = 0; i < VS; i += VL) {
const b_type vx = b_type::load(a + i, Tag());
const b_type scaled = xsimd::mul(vx, scale);
m_type idx = xsimd::to_int(scaled);
m_type idx_cos = xsimd::add(idx, quarter_pi);
idx = xsimd::bitwise_and(idx, mask);
idx_cos = xsimd::bitwise_and(idx_cos, mask);
const b_type sinv = b_type::gather(lookup_table_.values.data(), idx);
const b_type cosv = b_type::gather(lookup_table_.values.data(), idx_cos);
sinv.store(s + i, Tag());
cosv.store(c + i, Tag());
}
for (; i < n; i++) {
std::size_t idx = static_cast<std::size_t>(a[i] * lookup_table_.SCALE) &
lookup_table_.MASK;
std::size_t idx_cos = (idx + Q_PI) & lookup_table_.MASK;
s[i] = lookup_table_.values[idx];
c[i] = lookup_table_.values[idx_cos];
}
}
lookup_table<NR_SAMPLES> lookup_table_;
};
template <std::size_t NR_SAMPLES> struct LookupXSIMDBackend<NR_SAMPLES>::Impl {
cosf_dispatcher<NR_SAMPLES> cosf_dispatcher_;
sinf_dispatcher<NR_SAMPLES> sinf_dispatcher_;
sin_cosf_dispatcher<NR_SAMPLES> sin_cosf_dispatcher_;
void init() {}
void compute_sincosf(std::size_t n, const float *x, float *s,
float *c) const {
xsimd::dispatch(sin_cosf_dispatcher_)(n, x, s, c, xsimd::unaligned_mode());
}
void compute_sinf(std::size_t n, const float *x, float *s) const {
xsimd::dispatch(sinf_dispatcher_)(n, x, s, xsimd::unaligned_mode());
}
void compute_cosf(std::size_t n, const float *x, float *c) const {
xsimd::dispatch(cosf_dispatcher_)(n, x, c, xsimd::unaligned_mode());
}
};
template <std::size_t NR_SAMPLES>
LookupXSIMDBackend<NR_SAMPLES>::LookupXSIMDBackend()
: impl(std::make_unique<Impl>()) {}
template <std::size_t NR_SAMPLES>
LookupXSIMDBackend<NR_SAMPLES>::~LookupXSIMDBackend() = default;
template <std::size_t NR_SAMPLES>
void LookupXSIMDBackend<NR_SAMPLES>::init(size_t) {
impl->init();
}
template <std::size_t NR_SAMPLES>
void LookupXSIMDBackend<NR_SAMPLES>::compute_sinf(const std::size_t n,
const float *x,
float *s) const {
impl->compute_sinf(n, x, s);
}
template <std::size_t NR_SAMPLES>
void LookupXSIMDBackend<NR_SAMPLES>::compute_cosf(const std::size_t n,
const float *x,
float *c) const {
impl->compute_cosf(n, x, c);
}
template <std::size_t NR_SAMPLES>
void LookupXSIMDBackend<NR_SAMPLES>::compute_sincosf(const std::size_t n,
const float *x, float *s,
float *c) const {
impl->compute_sincosf(n, x, s, c);
}
// Explicit instantiations
template class LookupXSIMDBackend<16384>;
template class LookupXSIMDBackend<32768>;